This application claims the benefit of Japanese Patent Application No. 2002-074734 filed Mar. 18, 2002 in the Japanese Patent Office, the disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention generally relates to a recording magnetic head used in a magnetic disk, a magnetic tape and the like, and a magnetic storage device using the same.
2. Description of the Related Art
In a magnetic storage device where information on a magnetic storage medium is recorded and reproduced, a head of a combined type is generally used. The combined type head is a head in which a magnetic head for reproducing using an MR element and the like is provided with a magnetic head for recording of an induction type made from a thin film.
In the magnetic storage device, an approach has been made with regards to the recording magnetic head to narrow the recording track width to increase the surface recording density. The narrowing of the track width is usually achieved by narrowing the core width of the recording magnetic head. However, this causes the track width to be less than or equal to 0.5 μm, causing a problem of recording blurs. The recording blur is a phenomenon in which, when recording information, the information tends to get recorded on the sides of the desired track or the information on the adjacent track tends to get erased. Therefore, if the recording blurs spread in the track width direction, the virtual track width increases and the narrowing of the track width is impeded. As a recording magnetic head that devised countermeasures against such recording blurs, a recording magnetic head in which a lower magnetic pole layer is provided with a lower sub magnetic pole in a direction facing an upper magnetic pole layer is known, as disclosed in for example, Japanese Laid-Open 2000-99918.
Furthermore, to further increase the surface recording density, a recording bit length or the length of 1 bit of information recorded on the magnetic recording medium is shortened. However, if the recording bit length is shortened, a demagnetizing field of the recording bit increases, and it becomes necessary to increase the coercive force of the magnetic recording medium to an extent sufficient enough to overcome this demagnetizing field. In response to this increase in coercive force, the recording magnetic head must magnetize such magnetic recording medium sufficiently. To this end, it becomes necessary to increase the recording magnetic field near the medium facing face of a gap layer of the recording magnetic head where the magnetic recording medium is located.
One of the methods of achieving the above is to narrow the surface perpendicular to a direction that magnetic flux of the lower sub magnetic pole of the recording magnetic head passes, that is, the surface perpendicular to the film thickness of the lower sub magnetic pole, to concentrate the leakage magnetic flux from the lower sub magnetic pole near the medium facing face of the gap layer where the magnetic recording medium is located, and to increase the recording magnetic field.